Climate, one of the main important elements of the natural environment, has a determining role in natural and human life. According to the recent climate change impact assessment studies framework; agriculture, vegetation, water resources and tourism are the sectors affected directly by temperature changes. Temperature, being one of the most important climatic parameters, has a direct impact on the hazelnut farming. In this study, the possible effects of temperature conditions on hazelnut farming in Turkey within the next 90 years were examined. For this purpose, Kocaeli, Sakarya, Düzce, Samsun, Ordu, Giresun and Trabzon provinces, which are the most favorable habitat for hazelnut cultivation in Marmara and Black Sea Region, were selected as study area.Hazelnut is a quite selective plant considering its climatic requirements. Unlike other types of fruits in temperate climate, it flowers during winter months. This is the most significant factor limiting the cultivation of hazelnut in many regions. It can be naturally cultivated under humid temperate climatic conditions. Regions with annual mean temperature of 13 - 16 °C and at a height below 1500 meters have the most favorable conditions for cultivation. The data on production of hazelnut (ton) and area (hectare) was taken as raw data from 15 - year period from 1993, when it started to be recorded reliably, to 2007. It was converted into a usable form through Matlab 7.0 program. The yield data which used for relationship between climate and yield were computed by dividing total yearly production. Meteorological station data of annual mean temperature which covering 1930-2007 period were examined to determine the present day temperature conditions.In order to identify future temperature conditions, temperature data set which obtained from regional climate modeling (RegCM3) according to the A2 scenario for future 90 years (2011-2020, 2021-2030,.....2091-2100) was investigated. Re-analysisdata covering 1960-1990 were used for reference period calculations. Since the goal here was to conclude an overview about the production quantity and farming area, hazelnut yield data (ton / hectare) obtained from hazelnut production (ton) and area (hec- tare), were used as agricultural data. At the first stage of the research, annual mean temperature data set covering 1930-2007 time period was analyzed from the view of conformity with the hazelnut's requiring temperature and altitude conditions for a favorable cultivation in the research area. Firstly, temperature data were corrected according to standard atmosphere lapserate (0.649/100 m). Then hazelnut farming areas were determined according to the hazelnut temperature conditions, between 13 -16 °C annual mean temperature limits. In the same manner, the areas below the limit altitude value 1500 meters height were determined. After these two defined areas according to hazelnut's temperature and altitude requests are combined together to estimate the layout of possible hazelnut cultivation area. At the second stage of the research, detailed statistical analyses were performed to investigate the relationship between temperature conditions and hazelnut yield data. In order to examine this relationship Pearson correlation coefficient analysis was applied to temperature conditions and hazelnut yield. According to this analysis, the relationship between annual mean temperature and hazelnut yield was determined to be at the statistically meaning level of p < 0.01 and over 50 %. As a result, it is clearly seen that annual average temperatures are highly effective on yield of hazelnut.For determining the effects of future temperature conditions on hazelnut farming, temperature data set which obtained from regional climate modelling (RegCM3) with A2 scenario for next 90 years was used. The data were handled with the flexible Mat-lab program code builded during the research. To do this analysis, average ten years were simulated by the Matlab program code and comprehensive graphical analyses were represented. A temperature increase up to 6°C in the region over the next 90 years was identified depending on the future climate scenarios. Therefore, it is concluded that the temperature change may cause horizantal and vertical movements of hazelnut farming areas. Taking this conclusion into account, it is predicted that hazelnut cultivation in the coastal zone of 0-250 meters height can be negatively affected and areas over 1500 meters height which are not suitable for farming today can become favorable for hazelnut planting due to vertical area changes.